Several compelling reasons drive some U.S. birds to initiate breeding activities well before the official arrival of spring. The aim of the birds is always the same – to raise healthy offspring and give them, in turn, the best chance of breeding success. It is actually quite a simple combination of factors that influence an early start to breeding:
- Territory competition
- The length of time the chicks are dependent
- Availability of food
Here are some examples of birds that start to nest when we are all still shivering.
Great Horned Owls
Great Horned Owls are known for their early nesting habits, and this behavior is driven by a combination of factors related to their life history and ecological adaptations. These large owls are opportunistic predators, and their diet primarily consists of rodents, rabbits, and other small mammals. These prey animals become more active and abundant in late winter and early spring. Nesting early allows the owls to have their chicks at the stage where they require the most food when prey is readily available.
The chicks of Great Horned Owls also have a relatively long nestling period, requiring several weeks to develop and fledge. Starting early ensures that the young owls have sufficient time to mature before the onset of harsh weather or potential food shortages. Establishing and defending a territory takes time and energy so nesting early allows the owls to secure prime nesting sites and establish their territories before other competing species begin breeding.
Great Horned Owls do not build their own nests but typically use abandoned nests of other large birds, such as hawks, eagles, or crows. They may also use tree cavities, cliff ledges, or even man-made structures. Courtship begins well before nesting, often in late winter with males performing elaborate courtship displays, including vocalizations and aerial maneuvers, to attract females. Once a pair bond is established, they select a suitable nest site.
The timing of egg laying can vary depending on location and weather conditions and it is not uncommon for them to lay on top of snow. The female primarily incubates the eggs, while the male provides food. Incubation lasts for approximately 30 to 37 days and once the chicks hatch, both parents participate in feeding and caring for them. The chicks fledge at around 9 to 10 weeks of age, but they remain dependent on their parents for several more weeks.
Great Horned Owls are well-adapted to cold weather. They have thick plumage, and the ability to conserve heat. This allows them to nest in very cold conditions and protect their chicks.
Bald Eagles
Bald Eagles, like the owls above, are early nesters for reasons tied to the demands of raising their young. Raising eaglets is a lengthy process, from incubation to fledging. Early nesting ensures the young have ample time to develop and become independent before winter sets in.
These eagles time their nesting to coincide with the availability of their primary food sources, such as fish. Early nesting allows them to capitalize on early fish runs and the thawing of waterways. Spring can also bring unpredictable weather and early nesting can help minimize the risks associated with unpredictable spring weather events. By having chicks well-developed by the time these events occur, they increase the chances of survival.
Bald Eagles have to establish and defend a large territory, which requires a lot of time and energy. Early nesting allows eagles to secure prime nesting sites and establish their territories before other eagles or competing species arrive. Bald Eagles build massive nests, often the largest of any North American bird. They typically build their nests in large, mature trees near water. Nest building and maintenance begin well before egg laying, sometimes months in advance. They keep the nest and will add to it every year.
Females lay their eggs in late winter or early spring, depending on the region. Incubation begins immediately after the first egg is laid and lasts for approximately 35 days. Both parents participate in incubating the eggs and caring for the chicks. After hatching, the chicks require extensive parental care, including feeding and protection. They fledge at around 10 to 12 weeks of age, but the young eagles remain dependent on their parents for several more weeks.
Ravens
Ravens are highly adaptable birds, and their early nesting behavior is influenced by a combination of factors related to their intelligence, resourcefulness, and ecological niche. They are opportunistic omnivores, so they have a very diverse diet. This means that they can capitalize on food sources that become available early in the year, such as carrion or early-emerging prey. This dietary flexibility allows them to sustain themselves and their young during the colder months.
Raising raven chicks requires a significant amount of time and effort and starting early allows them to complete the nesting process before the onset of extreme heat or other potential environmental challenges.
As territorial birds, establishing and defending a territory is crucial for breeding success. Nesting early gives them a head start in securing prime nesting sites and resources. Having said that, they are very adaptable, living in many different climates. This means they are able to change their nesting habits to suit the conditions.
Ravens are versatile nesters, building their nests on a variety of structures, including cliffs, trees, and man-made structures like bridges and towers. They often choose sheltered locations that provide protection from the elements and will often reuse nests. The nests are large and bulky, constructed from twigs, branches, and other available materials. Inside, they often line it with softer materials like fur, feathers, or moss. Incubation is primarily carried out by the female, while the male provides food. Both parents participate in feeding and caring for the chicks. Like our other examples, raven chicks require a long period of parental care before they become independent.
Eastern Phoebe
The Eastern Phoebe’s early nesting behavior is a combination of its migratory patterns, adaptability, and the resources it relies on. They are among the first flycatchers to return to their breeding grounds in spring and this early arrival gives them a head start in establishing territories and initiating nesting.
Phoebes are adaptable nesters, readily using a variety of sheltered locations, including natural ledges, rock outcrops, bridges, buildings and porches. This flexibility allows them to find suitable nest sites even when other birds are still migrating.
While insects are not as abundant in early spring, Eastern Phoebes are able to find enough to sustain themselves and their young. They are adept at catching insects on the wing, and their early arrival allows them to capitalize on the first emerging insects.
Eastern Phoebes often raise two, or even three, broods in a single breeding season so starting early allows them to maximize their reproductive output. These attractive flycatchers build cup-shaped nests made of mud, moss, and other plant materials, often choosing sheltered locations that provide protection from the elements. They often like to build the nest on a solid vertical surface.
Once eggs are laid, incubation is primarily carried out by the female. Both parents participate in feeding and caring for the chicks. They are fed exclusively on insects and the chicks fledge at around 15 to 17 days.
Final Thoughts
These North American birds start nesting early for a combination of strategic advantages related to survival and reproduction. Larger birds, or those with long nestling periods, need extra time to raise young before harsh winter conditions arrive. Other birds will nest early as they align chick-rearing with the surge of food sources (insects, rodents, fish) in early spring. Starting early also allows some birds to raise multiple broods within a single breeding season.
